/* server */
#include <ctype.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define SIZE sizeof(struct sockaddr_in)
main(){
  int sockfd;
  char c;
/* the local server port */
  struct sockaddr_in server = {AF_INET, 7000, INADDR_ANY};
/* the structure to put in process2's address */
  struct sockaddr_in client;
  int client_len = SIZE;
/* set up the transport end point */
  if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1){
    perror("socket call failed");
    exit(1);
  }
/* bind the local address to the end point */
  if ( bind(sockfd, (struct sockaddr *)&server,SIZE)==-1){
    perror("bind call failed") ;
    exit(1);
  }
/* sit in waiting for messages */
  for( ; ;){
  /* receives the message and stores client */
    if(recvfrom(sockfd, &c, 1, 0,(struct sockaddr *)&client,&client_len)==-1){
      perror ( " server: receiving" ) ;
      continue;
    }
    c = toupper(c);
    printf("%c",c);
  /* sends the message back came from */
    if( sendto(sockfd, &c, 1,0,(struct sockaddr *)&client,client_len) == -1) {
      perror("server: sending");
      continue;
    }
  }
}